Macular pigment spatial distribution effects on glare disability

AbstractPurposeThis project explored the relationship of the macular pigment optical density (MPOD) spatial profile with measures of glare disability (GD) across the macula.MethodsA novel device was used to measure MPOD across the central 16° of retina along four radii using customized heterochromatic flicker photometry (cHFP)at eccentricities of 0°, 2°, 4°, 6° and 8°. MPOD was measured as discrete and integrated values at all measured retinal loci. GD was calculated as a difference in contrast sensitivity (CS) between no glare and glare conditions using identical stimuli presented at the same eccentricities. GD was defined as [(CSNo Glare−CSGlare)/CSNo Glare] in order to isolate the glare attenuation effects of MPOD by controlling for CS variability among the subject sample. Correlations of the discrete and integrated MPOD with GD were compared.ResultsThe cHFP identified reliable MPOD spatial distribution maps demonstrating a 1st-order exponential decay as a function of increasing eccentricity. There was a significant negative correlation between both measures of foveal MPOD and GD using 6cycles per degree (cpd) and 9cpd stimuli. Significant correlations were found between corresponding parafoveal MPOD measures and GD at 2 and 4° of eccentricity using 9cpd stimuli with greater MPOD associated with less glare disability.ConclusionsThese results are consistent with the glare attenuation effects of MP at higher spatial frequencies and support the hypothesis that discrete and integrated measures of MPOD have similar correlations with glare attenuation effects across the macula. Additionally, peak foveal MPOD appears to influence GD across the macula

Apparatus and method for assessing visual suppression

A device is used to determine the presence of and the amount (depth) of visual suppression in a subject. The device includes a first light source emitting a first light and a second light source emitting a second light. Intensities of the light sources are independently controllable. A first filter disposed over one eye of the subject allows transmission of the first light and prevents transmission of the second light. A second filter disposed over the other eye of the subject allows transmission of the second light and prevents transmission of the first light. In a method of using the device, the intensity of at least one of the first and second lights is independently controlled, wherein the difference in intensities of the first and second lights at which the lights appear to be at equal brightness to the subject determines the amount of visual suppression in the subject. For the most up-to-date information about these patents, including the availability of Certificates of Correction, be sure to check the United States Patent and Trademark Office\u27s free, publicly accessible database: Patent Public Search https://ppubs.uspto.gov/pubwebapp/static/pages/landing.htmlhttps://irl.umsl.edu/patents/1002/thumbnail.jp

Visual detection by the rod system in goldfish of different sizes

New rods are continually generated and inserted across the entire differentiated retina in juvenile and adult goldfish; no other retinal cells share this characteristic. How does the preferential addition of rods affect visual function? To examine the relation between continued rod addition and visual sensitivity, we measured absolute threshold in fish of different sizes. Twenty-nine fish were trained in a classical conditioning paradigm and psychometric functions were obtained for each of them for detection of a 532 nm light 5 sec in duration, 140 deg in angular subtense, presented while the fish was fully dark adapted. We found that absolute threshold (expressed in terms of retinal photon density) was lower in larger fish, but by a very small amount: on average, large fish (15.4 +/- 0.5 cm standard body length) were 1.45 times more sensitive than small fish (4.3 +/- 0.3 cm). Morphometric analysis showed that the planimetric density of rods in goldfish retina increases at a similar rate between small and large fish, while the density of retinal ganglion cells declines between small and large fish (by a factor of 3.8). The ratio of rods to ganglion cells (a possible indicator of neural convergence) increased, but by a factor that is too large to reconcile with the psychophysical results (5.3 x ). The results suggest that absolute visual threshold in the goldfish is closely related to the density of rods in the retina.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27508/1/0000552.pd

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Retinal Ganglion Cell Physiology (Morphology and Function)

Retinal ganglion cells have been classified into different types by a variety of techniques. Many of these techniques are based upon the cell's physiological response to a light stimulus. Among the most extensively studied types include: ON-OFF center cells (e.g.. Kuffler, 1953), color coded cells (e.g.. Gouras and Zrenner, 1981), and "other" conduction properties ("fast" vs "slow" conduction, "X-Y-W" cells, see e.g. , Lennie, 1980)

Rod Outer Segment Length and Visual Sensitivity

Detection threshold for the rod system was measured psychophysically in adult goldfish before and after exposure to constant illumination of 340 lux (91 /iW/cm 2 ) for 7 days. As shown in the previous paper, rod outer segment (ROS) length increases an average of 60% under these conditions. The present work shows that visual sensitivity also increases, in approximate proportion to the additional optical density predicted by the longer ROSs. These results are the first to show that exposure to constant light can enhance visual sensitivity. They imply further that detection threshold is related to ROS length. Apparently, the photopigment in the ROS tips that is normally shed on a daily basis retains its photon-catching ability. Invest Ophthalmol Vis Sci 31:2320-2325,199

Influence of macular pigment optical density spatial distribution on intraocular scatter

Purpose: This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). Methods: A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16° using a 1° stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1°, 3.3°, 10° and 16° diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. Results: Spatial mapping identified mean values for discrete MPOD [0.32 (s.d. = 0.08)], MPOD summed across central 1° [0.37 (s.d. = 0.11)], MPOD summed across central 3.3° [0.85 (s.d. = 0.20)], MPOD summed across central 10° [1.60 (s.d. = 0.35)] and MPOD summed across central 16° [1.78 (s.d. = 0.39)]. Mean intraocular scatter was 0.83 (s.d. = 0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1° were near significance. Conclusions: While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device